The school announced the purchase during a fundraiser Saturday. It will pay $11.6 million to buy, renovate and seismically upgrade the building.

Northwest Academy, founded in 1996, has been looking to buy a permanent space for 10 years, administrators say. It serves 139 students in grades six-12.

The school currently leases 28,000 square feet in four nearby buildings. Its new building is five stories tall and has 70,000 square feet of space.

The YWCA announced it would sell the building in December 2010, as well as lay off staff and eliminate services. The organization said it was struggling because of investment losses and government funding cuts.